After Installing 3rd Party VISA Software NI VISA No Longer Works

Issue Details

• When I had just NI-VISA installed on my system, I was able to identify and communicate successfully with my instruments in Measurement and Automation Explorer (MAX), LabVIEW, or other development environment. After installing another vendor's version of VISA, (ex: TekVISA or Keysight VISA), I can no longer identify or communicate with my COM ports or VISA instruments.
• After installing 3rd party software, NI-VISA passport drivers stopped working. What is causing this?
• Non-NI software causes NI-VISA to stop working. However, if I reinstall NI-VISA again, it works. Why is this happening?

Solution

Only one 32-bit VISA implementation can be configured as primary on a system at a given time. This primary VISA acts as the core VISA library of the system. In the case described above, NI-VISA was initially installed as primary and then changed to secondary when the second VISA implementation was installed. To resolve this issue, follow the steps below.

Verify Which VISA Implementation Is Primary

First, verify that NI-VISA is not currently installed as primary on your system by following these steps:

1. Navigate to the appropriate directory below based on the bitness of your OS and locate visa32.dll:
   • 32-bit systems: C:\WINDOWS\system32
   • 64-bit systems: C:\WINDOWS\sysWOW64
2. Right-click on visa32.dll and select Properties.
3. Find the copyright information:

• On Windows Vista/7/8/10: Navigate to the Details tab:

• On Windows XP: Navigate to the Version tab:

If the copyright information states National Instruments, then NI-VISA is set to be the primary VISA on your system. If another company is stated, then follow the steps below to make NI-VISA primary.

 

Set NI-VISA as Primary

If NI-VISA is not the primary implementation, you can reset it to be primary through MAX or repairing the NI-VISA driver.
 

Option 1: Set VISA as preferred in MAX

1. In MAX, expand the Software tab and navigate to your version of NI VISA.
2.  Select the VISA Options tab at the bottom of the window and then Conflict Manager. Under Preferred VISA, select National Instruments VISA.

Option 2: Repair NI-VISA

1. Navigate to the appropriate directory below based on the bitness of your OS and locate visa32.dll:

   • 32-bit systems: C:\WINDOWS\system32
   • 64-bit systems: C:\WINDOWS\sysWOW64
2. Rename visa32.dll to an alternate name, such as visa32.dll.bak.

2. Repair the NI-VISA driver. 
3. Reboot your computer.

Additional Information

• Some 32-bit VISA implementations support being installed as secondary, which allows them to be installed side-by-side with 32-bit NI-VISA. For more information, see the Related Links below or contact the vendor.
• The primary and secondary VISA designations apply only to 32-bit implementations of VISA. Multiple 64-bit implementations of VISA can be installed to a system without running into this problem.